Embodiments of the present invention are related to control systems and, in particular, to an acceleration estimator for speed rate control.
FIG. 1 shows a basic control system 100. A controller 102, can be used to regulate a plant 104, such as a motor, generator, or other system under control, based on a measurable output 106 of the plant. For example, a furnace controller may operate to maintain the output temperature of a furnace (e.g., the plant) at a preset temperature, or a motor controller may operate to maintain an output speed of a motor (e.g., the plant) at a preset speed. The output 106 of the plant can be fed back as feedback signal 108. Feedback signal 108 can be compared 110 to an input 112 (e.g., a desired output value) and the difference, error signal 114, can be input to controller 102. Based on the error signal 114, a control signal 116, can be provided to plant 104 to minimize the difference between the input 108 and the output 106, by increasing or decreasing the output 106, as needed.
In FIG. 1, a single output value is monitored and used for control. However, plants can be controlled in various ways based on the number of controllable inputs and outputs. For example, an electric motor may be controlled based on its speed, power, and/or torque. In such a case, a speed regulator, power regulator, and torque regulator may each monitor a corresponding output and provide a different control signal in response. A plant may be operated in different modes, depending on which controllable output is being controlled. For example, when a motor is operated in a speed control mode, the motor may be controlled to maintain an output speed at a preset value (e.g., based on the input 112), without controlling other controllable outputs.
However, problems occur where operating parameters of a plant need to be limited regardless of the mode in which it is operating, particularly where the operating parameters cannot be directly correlated with the output in each mode.
Embodiments of the invention address these and other problems.